B.how to do 缺少成分 how to do it
A.what to do it 缺少成分 .what to do with it.what to dowithit 没有with为什么不可以呢???whatcanidowithit？我对它可以做些什么呢？dowith 是处理的意思，词组哦哦 如果是what to do的话就可以选它了吧??嗯，说对了 what to do就可以了